SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6871de678df599391d39592dd9d654c29eb3d4859460cae9f42cd6535f495a5' 
  AND token = 'YUEqrtSXyYeUSw7UEvdG/M2rRbWYi0i4cNssc44wRuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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