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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a31771d5f4f535ebe51053c30473eb74b2b438b31a15a489dab7ebb3547f34df' 
  AND token = 'oPMIwdP+dxuaj4vf7EuzzcsbR6Du62l0PmIkX1x8kQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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