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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f83b61c13cdef33d97cd2cd689c6fe7df3074413fa6e2d5cf7b46a3104cbfdad' 
  AND token = 'EuOTxyQmd0TGbkVBGlKRw3MuSrFxqKW2v3dqujWt+eE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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