SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5404f5e7691fd0286d40a384aa59d78966fdb989236d556bb7ea1bc852229fd' 
  AND token = 'F4GWh4/o0Ds9vZ/FpEBunloWEgzk7a7tLjBEYa0vrq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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