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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55af90ab8b7b5c8b440244ca38a9265075693a130288b1e34f37f69f94fb2be' 
  AND token = 'vLpb1rYlvfJ3PHkDbfWS7aCL3QyuolRvW2olhfg7/Lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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