SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e63aa2986748e3b959a2f533a6d0b3cd1543dc90c48e3be584ba2f7613907a40' 
  AND token = '6K+hjK9X+j4hEoq3vGAVv1rlETSzrI5wXyAru+Xoh/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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