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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5c0f8b66e4ccbfb75f1d5417c6193092a81602a78063917566dc4f2f1c0bb92' 
  AND token = 'PGZ3aHnOnuXh1uLl1ycOUdOWxfjI6E+Al3vk/OpEv+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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