SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3819588ee79462b9f4d9485f3edce6ee5fd300fb1ba7de7516e27ffc9bde270' 
  AND token = 'NbpCmVJrcZ8i9xetC/v8lhf4vBVElWx1DsEeRRy0xA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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