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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ad2755ba761231a0c07519c801ea921b5c2a52c5621f2e17f5b04a7c8147a3c' 
  AND token = 'uEMIqKnLyR6ujTcRfGUeyVjK2Q2sKpatLNWQNRiXInY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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