SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1f2c76ca27fed123b504002edf5d43d773aaf60b311e2bcf3e93b4aa431e64c' 
  AND token = 'cMSTwrsEoF81LOOlINkEpkJcrystG04C9HMdHh0AlU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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