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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c19b0df3c6e4ea8c338b5fd5fc5ee820b2af6865c233cc17e2a14b26a87739c9' 
  AND token = 'Q4rcGQRTHsjBXb16kbU3+TitpWwk9RGAnCy5FVa21aA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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