SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20826d784a2a4ad94f2822adea9572ccbecd8cbcd5ed82f4318ea4a72e0b7c60' 
  AND token = '6C1RXbR5rZULbfK9mvZY7sqYRYSlyb+Dl/N3nrMqNkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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