SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e91b12dc60554bc60327b9545c9bcdfd71e7686ef5178dd18fcddf9fc99cb345' 
  AND token = '5zeF5bQdanPx8JJXzmyEqmXh1u1/NaWWQL7iHHO9Al0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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