SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c94c663e8300dce55636166f431e766340704c14f77cfc289cf725f9892af201' 
  AND token = 'C3/cAPefG3vTB+asSYLTBwEH7zSOxlteJWNk2ZZAi4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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