SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0126e50ddf7fc6120d12923a73f89535ad2cf4d0c2447210660c554e44bee635' 
  AND token = '2hfJDHe+HONZNKT4ZaekLNnfEUyvT2llWF8+r8nkfXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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