SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c42c0dcbdd0bef3734e64d387a916203672f815738343f1306cb485faed542a2' 
  AND token = '+anecesI1VCnXc8X/sFHLZwOshkIYJJOWnLPBbqglcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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