SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cc3db1d4250ba9d527b31e9c98277f255e282f381f3ad719e12a1e325f49fcb' 
  AND token = 'goribjD1L2VQrMJyGtK3HR9HLKz+QRhU1yw406UOPZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}