SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a8387bba24daf249dff80ce38864d238a7b88e9a24b53c0db6d21cb83493365' 
  AND token = 'S667UPwSNyidZC+HNizyuYTy7Zv896CyZ8mvMPcvjRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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