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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '740f23c8f247523085c3593bef9d6f19470b18d3afdbda58df040c83fe99ae0c' 
  AND token = 'JfE5ImwdPz7QmHSaJ7tuwd9P83QcrMVgnE0Htnt8H5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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