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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d944bd76e9e565c79fcf44045177d944399ecced0769a14b9ac2d2f2f79cf2' 
  AND token = 'SbDd6hcc6s6YrAyU4HJ7mKUnQBbOiPuDPNb5AzFzHGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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