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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '436b9c5e96ba440922a89d4df4a6ee61655f0bb28c87c45d0595dfeb7ba0652d' 
  AND token = 'PQGyN14Hp8U9nrFriGp86YdDFIWSLFtSmjl1d2KVYFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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