SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353f09f17e987ef695a6df07a422d550beb9867699568a0217513882b39950c6' 
  AND token = '1IZFYQz1Fe1dDSfnqpSaJSRTj2ePJodTS3AlBzTRYuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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