SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a1af41dc4ab8a4f58ea82a716cfeeadb13b70499a79e63b50945b20e1f645b' 
  AND token = 'ld7qZwdvfpJu80xDkx6FDWIwhM/TWQ8GqR3DgeQerqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00283

JSON explain

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