SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f5ce542155c0513ce510518ccfac98f819f796c0aa793ab04c8385875c52ef' 
  AND token = 'f6xjo2xbESMF5tVnPknqzgxhzUfMSewLJaN7Z6C0BzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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