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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5609f63be7e47c7a5d435ddde45048041b05e3cd4e2d85d2ee931d19ff97f91' 
  AND token = 'jng7aIAUx3+TE4kWcFaVyQ34WPlnN15E3m2FYsIjbN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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