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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '10dbf463b8c9289283e6b1dc0c8d2f888bd67e96234336be50f3bcd0ba205b62' 
  AND token = 'd5ZlKej+1wW3ksoKhBe7W/Q8dlBNfPsZdgHeVu+2p5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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