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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90a7b3a13e0d55f4f85e892b58d1364dddec6fb38f0c146dad8fed4548ffa78' 
  AND token = 'XNetR4MuQBu23Y/Im+UF1Ac7HjIJjK+B4bhvD43U83U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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