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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '208e9bc2d6acfb619e2c3813801e671a0fea6feb472d0882e8ec9457685bc4f4' 
  AND token = 'gPJLVEsAiLfNpOtOB21bak6bgVVUBwEbheJjB+TcUJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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