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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb2c70dce6ed7af3b10cd8d4d23df08ebd2f35ad76f2d1560ac6e377958cea3f' 
  AND token = 'n9RPsaCXt9oj+A295IpWAc4CwAQd/Z3gjvzM2XZEL7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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