SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c5a421dbff2c119071108ec245f9887a6893047b2850743fa479d3b035c1229' 
  AND token = 'OvRbtrjoQGrOmlUn4XZ0GsNcQV78QefGl7p2daLCf/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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