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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca9f75b435b4fe2392d6a717df0bfe2388e37a29e9b93b15fa9000433b9d5474' 
  AND token = '6NjczyUhkhFIBT1W2EpJ0lihTgvR/g7HkuBvfIc2CEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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