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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efec1d228ad714605cfe57ac878a83539658d7d9fec12d7ec0e4eeb91e1c1521' 
  AND token = 'MHbI94CmvFB3UkArGUEV1HmcgCW4dDE02geHGLCj2t4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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