SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4878b9c20a59eea98554484eb6d13c1099146e98f7765dd004f7180aba480f26' 
  AND token = 'yeQqmUpY79ucaG1Gj+dazRljIPBXJjiOkJliAM7dzMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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