SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c2e7c2312e551a798348708bc46763ef2651a70d1de846cc92551760575feed' 
  AND token = 'pLbdjTMpgZ5Y7FrzC+WnUwvHYJm6zdAeIOPNH+zrBJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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