SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c494b7fbfa94e1e44afb128e4834b99826f6777ad935ccb552d624c3e3c08aee' 
  AND token = 'n0fZzzS4nqbK7DPlI5D6xPJq2M48kLfvg+/2BBsVIJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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