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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b608a5f0f486df36b8fd42bb8865e1ebe830e7e41e1ebc936ae42c1ed41ace21' 
  AND token = 'AfYqZni3+B95T0XCRS+6z6nsr7bOc68G6r3e/JVRYy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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