SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fc3fd09c060ca3f45705ba6087b8e2f001e3122358b02b50df1694e5423bb75' 
  AND token = '56fGbPa+NnDdIIpcsQqxr+aMzh/JCt0n5nfqrcK8iKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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