SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '553637aa867a7fcb891364988e4af090d17cbfb03a51f92796fb264daf786cd9' 
  AND token = 'Qjn+AybWt5KHUtEM6e2SGuxYCYIFur40MWJH5Nu7OCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}