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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b34629e33d8efb9790449aaee05ac21749d347fb8dd5fab4bef208608e1a683' 
  AND token = '6htv5fZk4QcuyssvdEisB2MVZRK5dcBlUhxzicIT8GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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