SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4551ff32015beec986334ee9326c3feef48acf0de0a41b66fc1a247466f3f8a4' 
  AND token = 'lfjtppzXeW9ewWTujfeI+293z1JpHTGh6oDQ/hAxCIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}