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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d11a3894766b9878f6f5dfdad9a89df7e127dcc33afcbe30805c5c2b0aa3d21' 
  AND token = 'A8xUZI0/KF1qNZ69ZdVgarrmfbg0RPpv6+OylAPCF5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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