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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e210ed3af270cfcbdef0d362beeeb55a2bccd6b30b0496aac3d1a8c30450e0ab' 
  AND token = 'n+sU+cWg3RWiZjMtLX6eJIv4mrv1G/bd1MhXMZv5xlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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