SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddcd8689544a8b056c7571d1e98038c8dd5bde69dc18b540192fa14238295afc' 
  AND token = 'UqRdY+9qfgyVfH+s/HJ87VQWGHZVY+ohRprW+fbQlC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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