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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ad840460dbb2b7fb08f116a550cc3f0e3a1b0038f95a022b9b98dee8a615b72' 
  AND token = '4NrdI8Enq7p0vi0i7RXroy1aYMiyFKwShphtwGHyNNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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