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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f5ed9597ae4177976dd3f6b5776c0b9dd66e9b25f648b25c8f65933eff00d88' 
  AND token = 'fm3bSd7x8ttGs3uNoksiy7S8+Ch71Ioc5tr1ffWEeEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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