SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f7e63d4496d1dbdd6f858d01e677a223c2425fc7858c5bf5aa40c00a7b5078f' 
  AND token = '8RE5wY8o1Sq+hUPvUL1kKsVmB/Z1jhOhUDXpHNXdXg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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