SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61b21da28918fba50deba9e7a7b1eb0b52651b4f32028686434f2583e61126dd' 
  AND token = 'mRHsHp5WJp7h97lnVnuBcGUxljrP5PgbY2Sv9k0Mmzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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