SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71665eec83fc76a8651305abc494dc4741547677f203825e8cff41df088fd58e' 
  AND token = 'umCWPHheawrzfel9/hIYuoqsIYn+NCmovoMkjXDSTIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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