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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d9fa4e98549cfa281fe528d3d101dd2ab4c54990df5a905cb42664b81673458' 
  AND token = 'a+SK9Rs/c9sHkwfqwOqfb+Bg+wvHtxVA9/WVRkM1GG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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