SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6e043caf8f329a727beb347235f70a7cecf89e502adbda3f29c30e6e91bae554' 
  AND token = '2V3Qg8k96bvKB39hO70tnP+k1AqkWDGyX+mj3Gs+iYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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