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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb9ca6777f76339c7938d84bc4f8177a96a20c91ce85c2b84a7ae9ae589a00d4' 
  AND token = 'IPXORT5OQi8KSlp7AUUOeN8fT49fQe5IAfKiy2e3Y4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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