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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c39cb3a109aa38e6c43cda9669794df9fdbf55965e8d5359685b59b1a13160c' 
  AND token = 'sPE7wFUiEgQ7wXiXA3DZ5/1p+Rfq5hrxmYQvUS7qdAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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