SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18db35975441c213042e6de72e21c98af7294390889dd146c0c277fd9be2d6f2' 
  AND token = 'dayhhmNiN6Fx1lBW47POCG5v37nNmzSB96/oADGZlho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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