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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '26fa2b0d0c640fc7a38450fd46949ce4ab3d8c252e7cf561d7d8fc9474f6c6f4' 
  AND token = 'rsqbBc+0j9WHA8Xj3RbDOUzuJQISe0egddgq0Qgxpiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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