SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4df36f199c7fb2dccc230568384af7cf4472d2c985d542f29583357afa65043' 
  AND token = 'x1Zlh7jBtLOEEQN+rm1QoK/P7+VEPwOkv2kPjzSPfSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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