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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9555324c0fa027ec797326b3cd5f6736e62a02d08dda64c7d6504927aa61e8b' 
  AND token = 'ajJ8e/Cx+nZc8eNMSw11geuN8eKiJjp3S4Ao2NnekCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}