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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '21cb54fbc8973ed6e9b86086f2cf227be61624f1e68c2897a7fa806224348292' 
  AND token = 'rzazttODWdHzps3L6uFbn5SzwXD2rXkTICRNqT1x2i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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