SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6705b370f2c38b32fca48bd9310849753ed4264dbb345167d476c9eed9eb0480' 
  AND token = '5nh73s8UvegALyY8vd6mOcG/r+AzUdspF4MhXTGYI4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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