SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55830f00b5486ca1da6da117154fab19c78fb839fef4140b0b56d3b464857126' 
  AND token = 'ncxdeUE45eQhyLPIwVUj/PFVvwehzG/8ulGxmFhPiCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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