SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c8c0f916063c43723f0ec5ed7508da48786fe7dfd329da3259e0c102489e88' 
  AND token = '6fs2fls4BTduz7kNplZaYN/o0MD7Q0j9acUsLkE5I6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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