SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6504cf91f566a57aa754fdecfbb06ab36b0b651b20a69fadcb5e8f6e18232497' 
  AND token = 'hliF+mKlJoz5AftFHpaXi/Jo6/IUwgBb0YPh8qlE2C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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