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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a351aebb49b1293757a8653cb3efc06319a615fbe68d47a97099b3d9bb66c9' 
  AND token = 'DSDm/EQAC5b4QjJMIYrBQJbjq7B3SUsQ//R3YWxh8vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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