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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f15f5bd8b5773725e1e6c0e0f4cc2fabc3b3edc203a85c7e41210f45ee50b541' 
  AND token = 'RF9g1kdyBu/b/PTHW4x5oY2ZyMdlRPCD7TSYHXIKZB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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