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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56d12dc8fdd62d5f8ab8f9add993ade37ef4c36d612d5d5672ae2e6ed9193338' 
  AND token = 'fQHcErvFOoZZOofM6+QISqU45QhpxzvYB97qWeeO+ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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