SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94b6c6bc514b51d65791074caebedcabf2dc30eccc6a21f158f1cd69119da29d' 
  AND token = 'msKiGq5pnMtTTSDQre4zGggcGrICyH5p0kyUThokxRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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