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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '168bf8c0699861847a89ac0541e23e47e41e9766774bca522a7212ed542fd251' 
  AND token = 'GJYiTZMTehGzG2Shp6hoa6jnn78NQxiRzB4OyuMmOE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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