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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6a0ea96f97f7497b583376b5f2e1da621ee5ba390d816efed6628eae3a624aa' 
  AND token = 's5D9TQ8aIPdXQUhxGpfn4M8GMeuZn5V1M/LJz3Pi7Us=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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