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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b6c68f8d5ec76ea0db8ec6e1fa9ad2d86bb6cdb352498fce38c7bacd52a177' 
  AND token = 'BIzOQRfnTVnbignGT6POkIEFOzhJD49SpxaXDwc77Hk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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