SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e7c00e3f8ee4b2663ff633003131617408485e7a9d53a85ee463afb5c376e63' 
  AND token = 'eiqPJkklG6iUHzzIC16x/uzbSvx5zEfjRegfdInEC2o=' 
  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"
    }
  }
}