SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6735f31dfefd5afb03cf76e023f108f0bcd30af5ea3f45e382bab224a5cdac46' 
  AND token = '38erXCgDcTtxLU1nqySPZpmAEg4VNPojdjPEQaPxO/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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