SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b921b06e002d4f7838b27dc7fdaff59292b2da68c30189c7c1b224eb14d0d66d' 
  AND token = 'pb7CVvD3+r6qk0+9JJ5pik1WGtpFEjUKLxekh/zMiHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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