SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd234d5a0b655e20a09a414f077e6976b2983191344e23abd626300131b43150c' 
  AND token = 'xDVpcSIgHsjWWXDeyh/tyPIl3oziBxKg1xBmC0ztZhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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