SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '303738bd6c21a2ef5c889e313c0faa491fb63e47528970a33cfc43680187a933' 
  AND token = 'hxPPGdjyJFEqUpAwCPQKpwkOmX6wcgXh3BIoYec54I4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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