SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca6edf458b814ff3e159829d027647b2ae1ef12178a9292b73e08481fa54e20b' 
  AND token = 'O4+UFxr9YntWVQ6pkfNMr6tqi2zn7hX3DHmMLh/jK+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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