SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e5d0d5cf1391a617346fef41105cabf58c3a65a49dea33234970c88c6767840' 
  AND token = 'Z6ARMq6jLjGjdVJMGia1w+NXVmNviDwZFuINV1aH3b4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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