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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a38fb86d3c2bc522234f5e69308d4b115e7f1de4ec6343667184a47b4bb0d0e4' 
  AND token = 'B39ilECWfjRRAHUKcP9J3KtAiSdHGG4dzqpz2EYo5Sc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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