SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34b81c5782852fcd1f047db76768e914a5636aae2534b83adc558328d7eccc80' 
  AND token = '+/Lu6q1rYzddQDxFRGpR1trsj2fwBMFhWda0SZ2o+lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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